Glioma is the most common subtype of primary brain tumor in adults. While gene therapy using adenoviruses to deliver Herpes Simplex Virus type 1 - thymidine kinase (TK) has shown complete tumor elimination in preclinical paradigms, transition to clinical applications has only provided modest extensions of survival. Additionally use of adenovirus clinically is hampered by pre-existing immunity to adenovirus found in most adults. Utilizing a macroscopic model of glioma, the combination of conditionally cytotoxic (TK) and immune stimulatory FMS-like tyrosine kinase 3 ligand (Flt3L) adenoviral gene therapy results in 80 percent survival in non-immunized animals. This therapy fails in animals with pre-existing immunity to adenovirus. We hypothesize that use of high capacity, gutless adenoviral vectors will allow tumor regression and prolong survival even in the presence of pre-existing immunity to adenovirus. Tumor regression observed in animals treated with TK/Flt3L is hypothesized to occur by activation of innate and adaptive branches of the immune system.